Alloy steel and method of making it



Patented Aug. 23,1927.

- UNITED STATES I 1,639,989 PATENT. OFFICE.

CHARLES TYNDALE EVANS, OF TI'IUSVILLE, PENNSYLVANIA.

ALLOY STEEL Ann METHOD OF MAKING I'r.

Rom-swing.

less. These alloys contain high percentages of chromium, forexample,from 9% to 16% (thus differing from the so-called highspeed steels whichcontain lower percentages of chromium)v and are not non-corrosive orstainless in the ingot form and prior to the hardening, althoughsomewhat more resistant to corrosion than are the com-' mon steels.Furthermore, the high chromium content of such alloys tends to render 20them brittle, so thatthe cost of working the material is high and isattended by considerable loss, thus rendering such articles made fromsteels unduly expensive. In fact some of the stainless steels on themarket prior to my invention do not develop their stainless propertiesuntil polished. Furthermore, on account of the highchromium content ofthese prior so-called stainless steels they are difficult to forge andwhen made into cutlery or the like do not maintain a good cutting edge.

Because of the necessity of hardening such prior so-calledstainlesssteels in order to develop the stainless properties, they have not beensatisfactory for some purposes where a non-corrosive steel wouldotherwise be valuable. For example, a strong and non-corrosive steelpump rod would be a valuable article, but those prior so-calledstainless steels which have suflicient strength were objectionable forsuch use because if hardened they could not be fitted with keyways orotherwise worked to the pro er dimen'sions. If worked to shape an workedby forgin and machinin as are the usual steels emp oyed for mac 'neryand used -45 without hardening, they were not trul non- Applicationfiled April 18, 1922. serial in. 555,280.

cutlery purposes, this alloy havin it is non-corrosive in all stagesprior and subsequent to heat treatment.

Although this material cannot really be hardened b heat treatment, it ishardened by mechamcal work. For example, after forging or rolling it isvery much harder than prior thereto. By non-corrosive, I mean, the alloyis practically unaffected by organic acids, weak inorganic acids, oralkalies, and is practically not corroded by the action of theatmosphere or salt-water.

I will now 've the formula for a ferrous alloy embodymg the desiredproduct in one of its preferred forms:

Per cent.

The principal remaining ingredient'is iron.

the I further advantage over the usual stee that The above may be termedan idealanalysis, which may not always be obtained in practice. Inregular manufacturing operations the alloy steel usually contains somephosphorous, and some sulphur. These are'impurities which should beavoided as much as possible. Also some copper may be found in the alloy,this usually being brought in with the iron. A small amount of copper,for example, about 0.3 5 percent, is not objectionable, particularly ifthe manganese content is kept as high as 1 per cent or is increasedsomewhat above this amount.

In actual practice, steel alloys have been produced which [have all theproperties desired and which have analyses falllng within the followinglimits:

About 0015 Sulphur The principal remaining ingredient was iron.

Generally speaking, steel alloys of the character contemplated by .theinvent1on should contain not substantially less than 0.40 per cent ofmanganese and not substan tially less than 0.50 per cent of silicon.

An important feature of my invention consists of the process for makingthe new product hereinbefore described. This process consists inpreparing a starting mixture of such ingredients and in such proportionsas will, when melted, give the new alloy steel hereinbefore described,and adding to this mixture prior to or at the time of melting it a smallamount of zirconium, usually 1n the form of ferro-zirconium orsilico-zirconium.

By this process the desired product 1s obtained with greater certaintyand with less care in operation.

' By the use of a restricted amount of the zirconium in the mix, nozirconium will be found on analysis of the resulting alloy steel, or atmost only such a small amount that it cannot be detected by the ordinarymethods of analysis employed in steel works.

As one example of a mix Which may be employed in my new process I submitthe' following:

Parts. Iron 650 Nickel shot 205 Ferro-chromium 108 Manganese metal 8 Themix was" melted in a crucible in the usual way, was cast into an ingotand then worked down, all as in the usual steel making processes. Oneproduct obtained from the above mix gave the following analysis:

Ferro-silicon S1l1co-z1rcon1um iron.

In making the mix it is advantageous to use an iron which has a lowcarbon content and which is freed from impurities as much as possible,particularly from sulphur and 'type corresponding to the so-calledNorway or Swedish iron would be satisfactory. While the mix set forthabove is particularly suitable for the purposes intended, it

is to beunderstood that certain variations are permissible Withoutdeparting from the invention. nium or its compounds, I may use cerium ortitanium with good results, these being added to the mixin about theproportions stated for the zirconium.

What is claimed is:

1. An alloy steel comprising the following ingredients in substantiallythe following percentages: chromium 3.50 to 7.75; nickel 10 to 20;carbon 0.40 to 1.00; manganese 0.40 to 2.50;*silicon 0.50 to 2.50; theremainder being principally iron.

2. An alloy steel comprising the following ingredients in substantiallythe following percentages: chromium 3.50 to 7.75; nickel 10 to 20;carbon 0.40 to 1.00; manganese 0.40 to 2.50; silicon 0.50 to 2.50;copper 0.05 to 0.35; the remainder being principally iron.

3. Analloy steel comprising chromium, nickel, carbon, manganese, siliconand iron, the percentage of nickel being not substantially less than10%; that of chromium from-3.50 to 7.75; of carbon from 0.40 to 1.00; ofmanganese 0.40 to 2.50; of silicon 0.50 to 2.50; the remainderbeingprincipally iron.

4. An alloy steel comprising chromium, nickel, carbon, manganese,silicon and iron, the percentage of carbon being not greater than 1%;that of nickel being not substantially less than 10%; that of chromiumfrom 3.50 to 7.75; that of manganese from 0.40 to 2.50; that of siliconfrom 0.15 to 2.50; the remainder being principally iron.

In testimony whereof, I have hereunto set my hand.

CHARLES TYNDALE EVANS.

For example, instead of zirco-

